Polypeptides must often be stored prior to their use. When stored for extended periods, polypeptides are frequently unstable in solution (Manning et al., 1989, Pharm. Res. 6:903-918). To extend their shelf life, additional processing steps have been developed, such as drying, e.g., lyophilization. However, lyophilized pharmaceutical compositions are less convenient to use.
Typical practices to improve polypeptide stability can be addressed by varying the concentration of elements with the formulation, or by adding excipients to modify the formulation (See, for example, U.S. Pat. Nos. 5,580,856 and 6,171,586). However, the use of additives can still result in inactive polypeptides. In addition, in the case of lyophilization, the rehydration step can result in inactivation of the polypeptide by, for example, aggregation or denaturation (Flora et al., 1992, Pharm. Res., 9:33-36; Liu et al., 1991, Biotechnol. Bioeng., 37:177-184). Aggregation of polypeptides is undesirable, as it may result in immunogenicity (Cleland et al., 1993, Crit. Rev. Therapeutic Drug Carrier Systems, 10:307-377; and Robbins et al., 1987, Diabetes, 36:838-845).
Another way to improve polypeptide stability is to use L-arginine at a specific concentration (U.S. Pat. No. 7,648,702).
One of the polypeptides that is stored for up to two years prior to use is etanercept (Enbrel®, Immunex Corporation), which is a dimeric fusion polypeptide consisting of the extracellular ligand-binding portion of the human 75 kilodalton (p75) tumor necrosis factor receptor (TNFR) linked to the Fc portion of human IgG1. It consists of 934 amino acids and has an apparent molecular weight of approximately 150 kilodaltons (Physicians Desk Reference, 2002, Medical Economics Company Inc.) The Fc component of etanercept contains the constant heavy 2 (CH2) domain, the constant heavy 3 (CH3) domain and hinge region, but not the constant heavy 1 (CH1) domain of human IgG1. An Fc domain can contain one or all of the domains described above. Etanercept is usually produced by recombinant DNA technology in a Chinese hamster ovary (CHO) mammalian cell expression system.
The present invention provides novel stable liquid formulations of etanercept that allow its long-term storage.